MIGRATE_PAGES(2)                                                        Linux Programmer's Manual                                                       MIGRATE_PAGES(2)

NAME
       migrate_pages - move all pages in a process to another set of nodes

SYNOPSIS
       #include <numaif.h>

       long migrate_pages(int pid, unsigned long maxnode,
                          const unsigned long *old_nodes,
                          const unsigned long *new_nodes);

       Note: There is no glibc wrapper for this system call; see NOTES.

       Link with -lnuma.

DESCRIPTION
       migrate_pages() attempts to move all pages of the process pid that are in memory nodes old_nodes to the memory nodes in new_nodes.  Pages not located in any node
       in old_nodes will not be migrated.  As far as possible, the kernel maintains the  relative  topology  relationship  inside  old_nodes  during  the  migration  to
       new_nodes.

       The  old_nodes  and new_nodes arguments are pointers to bit masks of node numbers, with up to maxnode bits in each mask.  These masks are maintained as arrays of
       unsigned long integers (in the last long integer, the bits beyond those specified by maxnode are ignored).  The maxnode argument is the maximum  node  number  in
       the bit mask plus one (this is the same as in mbind(2), but different from select(2)).

       The  pid  argument  is  the ID of the process whose pages are to be moved.  To move pages in another process, the caller must be privileged (CAP_SYS_NICE) or the
       real or effective user ID of the calling process must match the real or saved-set user ID of the target process.  If pid is 0, then migrate_pages()  moves  pages
       of the calling process.

       Pages shared with another process will be moved only if the initiating process has the CAP_SYS_NICE privilege.

RETURN VALUE
       On  success migrate_pages() returns the number of pages that could not be moved (i.e., a return of zero means that all pages were successfully moved).  On error,
       it returns -1, and sets errno to indicate the error.

ERRORS
       EFAULT Part or all of the memory range specified by old_nodes/new_nodes and maxnode points outside your accessible address space.

       EINVAL The value specified by maxnode exceeds a kernel-imposed limit.  Or, old_nodes or new_nodes specifies one or more node IDs that are greater than the  maxi‐
              mum  supported  node  ID.  Or, none of the node IDs specified by new_nodes are on-line and allowed by the process's current cpuset context, or none of the
              specified nodes contain memory.

       EPERM  Insufficient privilege (CAP_SYS_NICE) to move pages of the process specified by pid, or insufficient privilege (CAP_SYS_NICE) to access the specified tar‐
              get nodes.

       ESRCH  No process matching pid could be found.

VERSIONS
       The migrate_pages() system call first appeared on Linux in version 2.6.16.

CONFORMING TO
       This system call is Linux-specific.

NOTES
       Glibc does not provide a wrapper for this system call.  For information on library support, see numa(7).

       Use  get_mempolicy(2)  with the MPOL_F_MEMS_ALLOWED flag to obtain the set of nodes that are allowed by the calling process's cpuset.  Note that this information
       is subject to change at any time by manual or automatic reconfiguration of the cpuset.

       Use of migrate_pages() may result in pages whose location (node) violates the memory policy established for the specified addresses  (see  mbind(2))  and/or  the
       specified process (see set_mempolicy(2)).  That is, memory policy does not constrain the destination nodes used by migrate_pages().

       The <numaif.h> header is not included with glibc, but requires installing libnuma-devel or a similar package.

SEE ALSO
       get_mempolicy(2), mbind(2), set_mempolicy(2), numa(3), numa_maps(5), cpuset(7), numa(7), migratepages(8), numastat(8)

       Documentation/vm/page_migration.rst in the Linux kernel source tree

Linux                                                                          2021-03-22                                                               MIGRATE_PAGES(2)